Hi im new to posting in forums but here we go. A week ago i bought a 95 cbr600 f3 with all the fairings off, they were turning it into a street fighter. They started it infront of me and it ran fine except for when you twisted the throttle it died. Bought the bike, brought it home, took carbs off, cleaned thoroughly. Amongst taking bike apart. I noticed air filter was the wrong size.so to compensate til i heard her run again, i just put filter in air box, tightened up, and put duct tape around the seem. It has an after market headlight, and aftermarket gauge. While bike ran before i bought it i noticed the gauge wasnt reading, but was on. Amonst my inspections and fixes. Ive checked for spark, firing order, and coils. My fuel line ive bypassed the fuel pump, just to make sure the carbs were getting fuel. And my air intake system has some pieces missing tho its the same pieces ive had, when she ran infront of me before, i charged the battery, it has air, fuel and spark. I bypassed the kick stand switch and the neutral safety switch. Choke works, carbs are good, idle screw turned all the way in. What are my next steps in figuring out what is wrong with this thing?

 

Welcome to the forum. Not to nitpick, but you haven't really described the problem very well. Is it a healthy crank with confirmed spark, or are we dealing with electrical shenanigans? What's your confidence level in the various modifications?

It sounds like you're comfortable mechanically, but without a bit more detail, we won't be much help. If you'd like some generic advice, rule out the basics first. If plugs indicate rich/lean, that'll be a clue to go back into the fuel system. The idle screw isn't supposed to be seated, so turn it out a couple turns if needed. Try the bike with a alternate power source. Check fuses. If the electrical seems weird, unpeel the electrical tape from all those wire splices and check for loose connections/bad grounds

https://cbrforum.com/forum/general-t...ureted-158288/

 

Yeah, apologies for being vague in areas. A lil frustrated when i wrote the post. The crank seems healthy with a 100% comfirmed spark. Id back fire ever couple tries at first, then i unscrewed the idle screw and it back fires like every 3-5 seconds now. The plugs are wet with a small amount of carbon at the tip. Gaps are set right and the tip isnt rounded, brand new sparkplugs from the looks of them. I did go thru all the electrical up to the aftermarket tach gauge on it and the frankstein headlight wiring. Tach turns on but doesnt read anything but the milage, havent rode it so.. cant assume too much on the hookup. And the headlights work. There cheap off road lights so they only come on when "highbeam" is pushed. Mechanically im confident in alot of what i do but.. all my other projects where basically stock and completely fine when i did them.

 

If you're getting spark on all four, then you should focus on the carbs. Before doing anything else though, I'd try a booster pack or other known power source. The last thing you want is to crank on the battery until it dies too

It sounds like it's flooded. I assume when you say backfire that you mean you can hear momentary ignition, but it won't fully start, right? If the last time the bike ran it stalled whenever you cracked the throttle, that also points to the carbs

1) Try with alternate battery
2) Drain old gas and replace fuel filter. Put fresh gas in, and mix in an octane booster if you like. Temporary tank makes this much easier
3) Check over the vacuum system to make sure major components aren't missing. If you've gone gravity-fed this is less likely an issue
4) Probably clogged pilot jets/badly adjusted carbs. If adjusting the idle screw doesn't help, you'll probably have to haul em back off and redo your cleaning. Poke all the orifice holes in all the jets with guitar wire or brass bristles
5) While the carbs are apart, check float height and fuel valves/seats. Check for torn diaphragms and inspect needles for damage
6) Set the pilot screws to factory recommendation
7) Reassemble and try it then. If no joy, try blasting some starting fluid down the carbs and see of that makes a difference. If not, you start to suspect problems with the engine itself

 

Sounds like you checked a lot & if you are getting a good spark, go back over the fuel system, as my RR-3 had the same - has good spark, clean new air filter & air box with no signs of failings, but my one wouldn't start either, So i pulled my whole fuel system & took every thing apart, & your one being carb & my EFI, they still both have fuel filters where when i pulled my fuel filter & it being a sealed metal unit all i could do was to get a 100ml syringe & set it up to a 8mm hose & started to back flush the filter & all this orange sludge started to ooze out, then after about 20 of these back flush's the 91 ron i was using to back flush the fuel filter started to come out as clear as it went in, & as well as a lot less force had to be used to push the fuel through, i was convinced the fuel filter was a large cause why, but now in 100% shape, I can't tell you if this was the fix all as i also put in a new fuel pump, new 6mm & 8mm fuel hose's & clamps, totally cleaned out the fuel rail & regulator, & using a injector cleaning tool & spray can of throttle body cleaner back flushed all 4 injectors before forward flushing all 4 injectors, & this with totally cleaning out the fuel tank, brought the old girl back to one 15 year old "Weapon". Dude if your fuel filter is a straight line set up just get a new one as being carb, they don't have to be those high pressure ones & will cost nothing from a auto shop, your hunt will be trial by do & starting at the least expensive part & try? just give that a go & see if you get any joy. Chris.W